Keychain always asks for email password

I have Snow Leopard, Mail, 1Password etc but since upgrading Mail constantly asks for my Comcast email password. I have checked Keychain & 1Password, all is correct. I notice also I am having the bouncing postage stamp icon for Mail & I then have to take the option Mailbox- Take all accounts online.
Everything else works once I enter the password but it's annoying. BTW of course I check "Remember..."
Any ideas?
p.s If this is not the right forum for this problem, what is?

Comcast's email servers have occasionally caused this problem and it's been reported on their own forums. I'm not having the issue at the moment though, so I suspect it might be your account settings.

Take a look at this site and see if your settings match the recommended ones.

Also, this is Comcast's official setup for Apple Mail, although it's a bit dated (looks like the Tiger version of Mail or earlier):

Welcome to Comcast customerCentral!

I have the same problem, but I'm with a Canadian provider (Bell). Doesn't happen often, but it does happen.